Also remember part of your payload of the Durango is not only passengers, the dog, misc in the rear but also the tongue weight of the trailer and the hitch.
Go on line or search here for instructions on how to weigh on a CAT scale, DO not unhook your trailer on the scale to get trailer weight. If their are no trucks near by other places like concrete plants, landfills, quarries, have truck scales but they are usually single pad & I would call first before going to see if they would allow you to use it. CAT scales are commercial can weigh buy axles & make their money weighing vehicles, reweighs the same day are $2-3.
Dry weight is what the trailer weighed leaving the factory, No propane, no water no supplies, no gear, no options (any added later). It is easy to get 1000 lbs or more added to dry weight. Several hundred lbs added will be propane, hitch / sway bars, hoses, cords, possible water, spare tire (they are optional & may have been weighed without one), battery. I have added close to 1000 lbs after dry weight just in thing that are attached to the trailer,